Overload protection device for cable strands

Abstract

An overload protection device for cable lines, and in particular in cranes, is provided, having at least one electronic overload safety means. The overload protection device is provided to prevent any kind of damage which can be caused by an overload. That is achieved by providing a mechanical or magnetic overload protection device (1) in addition to the electronic overload safety means. The overload protection device (1) is integrated into the cable line or arranged at the cable fixing point and responds when a permissible cable tension force is exceeded and implements a cable extension.

The invention claimed is: 
     
       1. An overload protection device for cable lines comprising:
 at least one electronic overload safety means, 
 a mechanical or magnetic overload protection device ( 1 ;  31 ;  51 ) configured to be integrated into the cable line or arranged at a cable fixing point and configured to respond when a permissible cable tension force is exceeded and implements a cable extension, 
 the mechanical or magnetic overload protection device ( 1 ;  31 ;  51 ) comprising:
 a housing ( 2 ;  32 ;  52 ) having an interior ( 3 ;  35 ;  53 ) and closed at one side, 
 a longitudinally slidably guided load pin ( 5 ;  33 ;  54 ) in the housing ( 2 ;  32 ;  52 ), having a shank ( 9 ,  36 ) and a piston ( 7 ,  34 ,  58 ) at an end thereof toward the closed side of the housing interior ( 3 ;  35 ;  53 ) and guided in the housing interior ( 3 ;  35 ;  53 ), and 
 a stroke force limiting device ( 6 ;  40 ;  59 ) fixing the load pin ( 5 ,  33 ,  54 ) in the housing ( 2 ;  32 ,  52 ) under normal operation, 
 wherein the stroke force limiting device ( 59 ) comprises two pressure rings ( 60 ,  61 ), at least one of the pressure rings ( 60 ,  61 ) having a peripherally extending inclined surface ( 62 ,  63 ), and wherein the load pin ( 54 ) includes a run-on inclined surface ( 65 ) in the region of the pressure rings ( 60 ,  61 ), positioned proximate the inclined surface ( 62 ,  63 ) of at least one of the pressure rings ( 60 ,  61 ), the run-on inclined surface ( 65 ) of the load pin ( 54 ) interacting with balls which are arranged about a periphery of the run-on inclined surface ( 65 ), the balls ( 66 ) being urged outwardly when a permissible maximum load is exceeded by means of the run-on inclined surface ( 65 ) of the load pin ( 54 ) and at least one of the pressure rings ( 60 ) is displaced in the longitudinal direction of the load pin ( 54 ) against the force of a first compression spring ( 67 ), whereby the load pin ( 54 ) is released and can move out of the housing ( 52 ) against the force of a second compression spring ( 70 ), 
 wherein an end of the shank ( 9 ;  36 ), remote from the piston ( 7 ;  34 ;  58 ), is accessible from an exterior of the device and connectable to the cable line, and the load pin ( 5 ;  33 ;  54 ) is released by the stroke force limiting device ( 6 ;  40 ;  59 ) toward an open side of the housing ( 2 ;  32 ;  52 ) when the permissible cable tensile force is exceeded, and 
 wherein a nut ( 68 ) having a male thread is screwed into a fixed female thread located in the housing interior ( 53 ) in a central region thereof, the first compression spring ( 67 ) being arranged between the nut ( 68 ) and an upper pressure ring ( 60 ) of the pressure rings ( 60 ,  61 ) and the second compression spring ( 70 ) being arranged between the nut ( 68 ) and the piston ( 58 ) guided in the housing interior ( 53 ) near the closed side of the housing ( 52 ) on the load pin ( 54 ). 
 
 
     
     
       2. The overload protection device according to  claim 1 , wherein the shank ( 9 ;  36 ) of the load pin ( 5 ;  33 ;  54 ) is longitudinally slidably guided by fitments fixedly arranged in the housing interior ( 3 ;  35 ;  53 ). 
     
     
       3. The overload protection device according to  claim 1 , wherein the housing ( 52 ) includes a removable cover ( 71 ) at its closed side. 
     
     
       4. The overload protection device according to  claim 1 , wherein the piston ( 58 ) is releasably fixed to the end of the load pin ( 54 ).